Microwave push-pull oower amplifier using metamaterial-based baluns

A new push-pull power amplifier using metamaterial (MM)-based baluns is developed in this paper. To effectively suppress the second harmonics from two power amplifiers in the push-pull circuit configuration, two MM-based baluns with a 79% out-of-phase bandwidth and an amplitude imbalance of 0.67 dB are employed as input and output circuitries. At 1.5 GHz, the developed push-pull power amplifier achieves a small-signal gain of 8.1 dB, a peak power-added efficiency (PAE) of 27.1%, and a second-harmonic suppression of 43.2 dB at 1-dB gain compression point.